Liquid crystal composition, liquid crystal device, display apparatus and display method

ABSTRACT

A liquid crystal composition, comprising: at least one mesomorphic compound represented by the following formula (I): 
     
         R.sup.1 --X.sup.1 --A.sup.1 --B--A.sup.2 --X.sup.2 --R.sup.2(I) 
    
     and at least one mesomorphic compound represented by the following formula (II): ##STR1## The liquid crystal composition is easily aligned by a simple rubbing method to provide a uniform monodomain and further provides wider driving voltage and temperature margins effective for providing a practical ferroelectric liquid crystal device.

FIELD OF THE INVENTION AND RELATED ART

The present invention relates to a novel liquid crystal composition, aliquid crystal device, a display apparatus and a display method, andmore particularly to a novel liquid crystal composition with improvedresponsiveness to an electric field, a liquid crystal device using theliquid crystal composition for use in a display device, a liquidcrystal-optical shutter, etc., a display apparatus using the device, anda display method using the composition and device.

The use of liquid crystal devices having bistability has been proposedby Clark and Lagerwall (e.g. Japanese Laid-Open Patent Appln. No.56-107216, U.S. Pat. No. 4,367,924, etc.). In this instance, as theliquid crystals having bistability, ferroelectric liquid crystals havingchiral smectic C-phase (SmC*) or H-phase (SmH*) are generally used.These liquid crystals have bistable states of first and second stablestates with respect to an electric field applied thereto. Accordingly,as different from optical modulation devices in which the conventionalTN-type liquid crystals are used, the bistable liquid crystal moleculesare oriented to first and second optically stable states with respect toone and the other electric field vectors, respectively. Further, thistype of liquid crystal has a Property (bistability) of assuming eitherone of the two stable states in response to an applied electric andretaining the resultant state in the absence of an electric field.

In addition to the above-described characteristic of showingbistability, such a ferroelectric liquid crystal (hereinafter sometimesabbreviated as "FLC") has an excellent property, i.e., a high-speedresponsiveness. This is because the spontaneous polarization of theferroelectric liquid crystal and an applied electric field directlyinteract with each other to induce transition of orientation states. Theresultant response speed is faster than the response speed due to theinteraction between dielectric anisotropy and an electric field by 3 to4 digits.

Thus, a ferroelectric liquid crystal potentially has very excellentcharacteristics, and by making use of these properties, it is possibleto provide essential improvements to many of problems with theconventional TN-type devices. Particularly, the application to ahigh-speed optical shutter and a display of a high density and a largepicture is expected.

A simple matrix display apparatus including a device comprising such aferroelectric liquid crystal layer between a pair of substrates may bedriven according to a driving method as disclosed in. e.g., JapaneseLaid-Open Patent Applications Nos. 193426/1984, 193427/1984, 156046/1985and 156047/1985.

FIGS. 4 and 5 are waveform diagrams showing driving voltage waveformsadopted in driving a ferroelectric liquid crystal panel as an embodimentof the liquid crystal device according to the present invention. FIG. 6is a plan view of such a ferroelectric liquid crystal panel 61 having amatrix electrode structure. Referring to FIG. 6, the panel 61 comprisesscanning lines 62 and data lines 63 intersecting with the scanninglines. Each intersection comprises a ferroelectric liquid crystaldisposed between a scanning line 62 and a data line 63 to form a pixel.

Referring to FIG. 4, at S_(S) is shown a selection scanning signalwaveform applied to a selected scanning line, at S_(N) is shown anon-selection scanning signal waveform applied to a non-selectedscanning line, at I_(S) is shown a selection data signal waveform(Providing a black display state) applied to a selected data line, andat I_(N) is shown a non-selection data signal waveform (providing awhite display state) applied to a non-selected data line. Further, at(I_(S) -S_(S)) and (I_(N) -S_(S)) in the figure are shown voltagewaveforms applied to pixels on a selected scanning line, whereby a pixelsupplied with the voltage (I_(S) -S_(S)) assumes a black display stateand a pixel supplied with the voltage (I_(N) -S_(S)) assumes a whitedisplay state. FIG. 5 shows a time-serial waveform used for providing adisplay state as shown in FIG. 7.

In the driving embodiment shown in FIGS. 4 and 5, a minimum duration Δtof a single polarity voltage applied to a pixel on a selected scanningline corresponds to the period of a writing phase t₂, and the period ofa one-line clearing phase t₁ is set to 2Δt.

The parameters V_(S), V_(I) and Δt in the driving waveforms shown inFIGS. 4 and 5 are determined depending on switching characteristics of aferroelectric liquid crystal material used.

FIG. 8 shows a V-T characteristic, i.e., a change in transmittance Twhen a driving voltage denoted by (V_(S) +V_(I)) is changed while a biasratio as mentioned hereinbelow is kept constant. In this embodiment, theparameters are fixed at constant values of Δt=50 μs and a bias ratioV_(I) /(V_(I) +V_(S))=1/3. On the right side of FIG. 8 is shown a resultwhen the voltage (I_(N) -S_(S)) shown in FIG. 4 is applied to a pixelconcerned, and on the left side of FIG. 8 is shown a result when thevoltage (I_(S) -S_(S)) is applied to a pixel concerned, respectivelywhile increasing the voltage (V_(S) +V_(I)). On both sides of theordinate, the absolute value of the voltage (V_(S) +V_(I)) is separatelyindicated. Herein, a voltage V₁ denotes the minimum absolute value of(V_(S) +V_(I)) required for switching from a white state to a blackstate by applying a voltage V_(B) ² at (I_(S) -S_(S)) shown in FIG. 4, avoltage V₂ denotes the minimum absolute value of (V_(S) +V_(I)) requiredfor switching (resetting) a black state to a white state by applying avoltage V_(R) at (I_(N) -S_(S)), and a voltage V₃ is the maximumabsolute value of (V_(S) +V_(I)) required for retaining a white state,i.e., beyond which a pixel concerned written in white is unexpectedlyinverted into a black state by applying a voltage V_(B) ¹ at (I_(N)-S_(S)). In this instance, a relationship of V₂ <V₁ <V₃ holds. Thevoltage V₁ may be referred to as a threshold voltage in actual drive andthe voltage V₃ may be referred to as a crosstalk voltage. Such acrosstalk voltage V₃ is generally present in actual matrix drive of aferroelectric liquid crystal device. In an actual drive, ΔV=(V₃ -V₁)provides a range of |V_(S) +V_(I) | allowing a matrix drive and may bereferred to as a (driving) voltage margin, which is preferably largeenough. It is of course possible to increase the value of V₃ and thus ΔV(=V₃ -V₁) by increasing the bias ratio (i.e., by causing the bias ratioto approach a unity). However, a large bias ratio corresponds to a largeamplitude of a data signal and leads to an increase in flickering and alower contrast, thus being undesirable in respect of image quality.According to our study, a bias ratio of about 1/3-1/4 was practical. Onthe other hand, when the bias ratio is fixed, the voltage margin ΔVstrongly depends on the switching characteristics of a liquid crystalmaterial used, and it is needless to say that a liquid crystal materialproviding a large ΔV is very advantageous for matrix drive.

The upper and lower limits of application voltages and a differencetherebetween (driving voltage margin ΔV) by which selected pixels arewritten in two states of "black" and "white" and non-selected pixels canretain the written "black" and "white" states at a constant temperatureas described above, vary depending on and are inherent to a particularliquid Crystal material used. Further, the driving margin is deviatedaccording to a change in environmental temperature, so that optimumdriving voltages should be set in an actual display apparatus accordingto a liquid crystal material used and an environmental temperature.

In a practical use, however, when the display area of a matrix displayapparatus is enlarged, the differences in environmental conditions (suchas temperature and cell gap between opposite electrodes) naturallyincrease, so that it becomes impossible to obtain a good quality ofimage over the entire display area by using a liquid crystal materialhaving a small driving voltage margin.

In order to realize such a matrix display apparatus, an alignmentcharacteristic of the liquid crystal material used becomes an importantfactor.

On the other hand, the liquid crystal materials assuming a chiralsmectic C phase (SmC*) are liable to cause a zig-zag defect or analignment defect at an area around a gap-retaining material such asspacer beads in a liquid crystal cell when the above rubbing (treatmentis conducted. Further, the liquid crystal materials assuming SmC* arealso liable to cause an alignment defect due to difference in rubbingstate of an alignment film. The difference is caused by. e.g., surfaceunevenness of the alignment film due to the liquid crystal devicestructures used.

These problems may be attributable to the fact that an SmC* phase isprovided through some phase transitions from an isotropic phase ontemperature decrease in many cases and is closer to a crystal state thana nematic phase.

The above-mentioned alignment defect leads to drawbacks of lowering inbistability characteristic of the SmC* liquid crystal materials,lowering in image quality and contrast or occurrence of crosstalk.

SUMMARY OF THE INVENTION

The present invention is accomplished in order to solve theabove-mentioned problems of the conventional liquid crystal devices andaims at realizing a ferroelectric liquid crystal device which isexpected to be applied to a high-speed optical shutter and a display ofa high density and a large picture.

An object of the present invention is to provide a liquid crystalcomposition which is easily aligned by simple rubbing treatment andprovides a monodomain having a uniform alignment characteristic and nodefects.

Another object of the present invention is to provide a liquid crystalcomposition having a large driving temperature margin and a wide drivingtemperature margin affording satisfactory drive of entire pixels evenwhen some degree of temperature fluctuation is present over a displayarea comprising the pixels of a liquid crystal device.

A further object of the present invention is to provide a liquid crystaldevice using such a liquid crystal composition and showing improveddriving and display characteristics, and a display apparatus using thedevice and a display method using the composition or the device.

According to the present invention, there is provided liquid crystalcomposition, comprising:

at least one mesomorphic compound represented by the following formula(I):

    R.sup.1 --X.sup.1 --A.sup.1 --B--A.sup.2 --X.sup.2 --R.sup.2(I),

wherein R¹ and R² independently denote a linear or branched alkyl grouphaving 1-18 carbon atoms capable of including one or non-neighboring twoor more methylene groups which can be replaced with at least one speciesof --O--, --CO--, --COO--, --OCO--, --OCOO-- or --CH(X)-- with theproviso that --O-- cannot directly be connected to --O-- and X denoteshalogen; X¹ and X² independently denotes a single bond, --O--, --COO--,--OCO-- or --CO--; B denotes ##STR2## A¹ denotes a single bond, ##STR3##A² denotes a single bond, --A³ -- or --A³ --A⁴ -- wherein A³ and A⁴independently denote any one of A¹, ##STR4## and Y¹ and Y² independentlydenote any one of hydrogen, F, Cl, Br, --CH₃, --CN and --CF₃ ; and atleast one mesomorphic compound represented by the following formula(II): ##STR5## wherein R³ and R⁴ independently denote a linear orbranched alkyl group having 1-18 carbon atoms capable of including oneor non-neighboring two or more methylene groups which can be replacedwith at least one species of --O--, --CO--, --COO--, --OCO--, --OCOO--or --CH(X)--with the proviso that --O-- cannot directly be connected to--O-- and X denotes halogen; X³ and X⁴ independently denotes a singlebond, --O--, --COO--, --OCO-- or --CO--; Z¹ denotes a single bond.--COO-- or --OCO--; A⁵, A⁶ and A⁷ independently denote a single bond,##STR6## Y³ and Y⁴ independently denote halogen, --CH₃ or --CF₃ ; and kis 0 or 1 with the proviso that X³ is a single bond when A⁵ is a singlebond, and X⁴ is a single bond when A⁶ is a single bond and k is 0.

According to the present invention, there is also provided a liquidcrystal composition containing the above composition and a mesomorphiccompound represented by the following formula (III): ##STR7## wherein R⁵denotes a linear or branched alkyl group having 1-18 carbon atomsoptionally having a substituent; X⁵ denotes a single bond, --O--,--COO-- or --OCO--; Z² denotes a single bond, --COO--, --OCO--, --COS--or --SCO--; X⁶ denotes --OCH₂ --, --COOCH₂ --, --OCO-- or ##STR8##wherein k is an integer of 1-4; ##STR9## denotes ##STR10## and u is aninteger of 1-12.

The present invention provides a liquid crystal device comprising a pairof electrode plates and the liquid crystal composition described abovedisposed between the electrode plates.

The present invention further provides a display apparatus comprisingthe above-mentioned liquid crystal device, and voltage application meansfor driving the liquid crystal device.

The present invention still further provides a display method using theliquid crystal composition or the liquid crystal device described aboveand switching the alignment direction of liquid crystal molecules byapplying voltages to the liquid crystal composition to effect display.

These and other objects, features and advantages of the presentinvention will become more apparent upon a consideration of thefollowing description of the preferred embodiments of the presentinvention taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic sectional view of a liquid crystal display deviceusing a liquid crystal composition assuming a chiral smectic phase;

FIGS. 2 and 3 are schematic perspective views of a device cellembodiment for illustrating the operation principle of a liquid crystaldevice utilizing ferroelectricity of a liquid crystal composition;

FIG. 4 shows unit driving waveforms used in an embodiment of the presentinvention; FIG. 5 is time-serial waveforms comprising a succession ofsuch unit waveforms;

FIG. 6 is a plan view of a ferroelectric liquid crystal panel having amatrix electrode structure;

FIG. 7 is an illustration of a display pattern obtained by an actualdrive using the time-serial waveforms shown in FIG. 5;

FIG. 8 is a V-T characteristic chart showing a change in transmittanceunder application of varying drive voltages;

FIG. 9 is a block diagram showing a display apparatus comprising aliquid crystal device utilizing ferroelectricity of a liquid crystalcomposition and a graphic controller; and

FIG. 10 is a time chart of image data communication showing timecorrelation between signal transfer and driving with respect to a liquidcrystal display apparatus utilizing ferroelectricity and a graphiccontroller.

DETAILED DESCRIPTION OF THE INVENTION

Preferred examples of the mesomorphic compound of the formula (I) mayinclude those represented by the following formulas (Ia) and (Ig):##STR11##

In the above formula (Ia)-(Ig), R¹, R², B, X¹, X², Y¹ and Y² are thesame as defined above.

Preferred examples of B in the above formulas (Ia)-(Ig) may include##STR12## Preferred Examples of X¹ and X² may independent include asingle bond, --O--, --COO-- and --OCO--. Further, Y¹ and Y² maypreferably be Cl or F, particularly F, respectively.

In the above-mentioned formula (I), preferred examples of R¹ and R² mayrespectively include those represented by the following groups (I-i) to(I-iv):

(I-i) an n-alkyl group having 1-16 carbon atoms, particularly 4-12carbon atoms;

(I-ii) ##STR13## wherein m is an integer of 0-6 and n is an integer of1-8 (optically active or inactive);

(I-iii) ##STR14## wherein r is an integer of 0-6, s is or 1, and t is aninteger of 1-12 (optically active or inactive); and

(I-iv) ##STR15## wherein p is 0 or 1 and x is an integer of 1-14.

Preferred examples of the mesomorphic compound of the formula (II) mayinclude those represented by the following formulas (IIa) to (IIq):##STR16##

In the above, R³, R⁴, X³, X⁴, Z¹, Y³ and Y⁴ are the same as definedabove.

In the above formulas (IIa)-(IIq), further preferred examples of themesomorphic compound of the formula (II) may include those representedby the following formulas (IIaa) to (IIna): ##STR17##

In the above, R³, R⁴, X³, X⁴, Y³ and Y⁴ are the same as defined above.

In the above-mentioned formula (II), preferred examples of R³ and R⁴ mayrespectively include those represented by the following groups (II-i) to(II-iv):

(II-i) an n-alkyl group having 2-16 carbon atoms, particularly 4-14carbon atoms;

(II-ii) ##STR18## wherein m' is an integer of 0-6 and n' is an integerof 2-8 (optically active or inactive);

(II-iii) ##STR19## wherein r' is an integer of 0-6, s' is 0 or 1, and t'is an integer of 1-12 (optically active or inactive); and

(II-iv) ##STR20## wherein p' is 0 or 1 and x' is an integer of 1-14.

Preferred examples of the mesomorphic compound of the formula (III) mayinclude those represented by the following formulas (IIIa)-(IIIf):##STR21##

In the above, R⁵, X⁵, X⁶ and u are the same as defined above. In theabove formulas (IIIa) to (IIIf), further preferable examples may includethose of the formulas (IIIa) to (IIIc). Further, X⁵ and X⁶ in theformulas (IIIa) to (IIIf) may preferably include the followingcombinations (III-i) to (III-v):

(III-i) X⁵ is a single bond and X⁶ is --O--CH₂ --;

(III-ii) X⁵ is a single bond and X⁶ is --COO--CH₂ --;

(III-iii) X⁵ is a single bond and X⁶ is --OCO--;

(III-iv) X⁵ is --O-- and X⁶ is --O--CH₂ --; and

(III-v) X⁵ is --O-- and X⁶ is --COOCH₂ --.

Representative reaction schemes A and B for producing the mesomorphiccompounds represented by the above formula (I) are shown below.##STR22##

In the above, R¹, R², X¹, X², A¹ and A² are the same as defined above.##STR23##

In the above, R¹, R¹, X¹, X², A¹ and A² are the same as defined above.

Specific examples of the mesomorphic compounds represented by theabove-mentioned general formula (I) may include those shown by thefollowing structural formulas. ##STR24##

Representative examples of synthesis of the compounds of the formula (I)are shown below.

SYNTHESIS EXAMPLE 1

2-(p-octylphenyl)-6-hexylbenzothiazole (Example Compound No. 1-15) wassynthesized through the following steps i)-iii). ##STR25##

Step i) Production of 2-amino-6-hexylbenzothiazole

In a 2 liter-reaction vessel, 50.0 g (0.28M) of p-hexylaniline, 54.8 g(0.56M) of potassium thiocyanate and 400 ml of acetic acid were placedand cooled below 10° C. To the mixture, a solution of 45.0 g of brominein 135 ml of acetic acid was added dropwise in 40 minutes below 10° C.under strong stirring, followed by reaction for 1.5 hours below 10° C.After the reaction, 500 ml of water was poured into the reactionmixture, followed by heating to dissolve the resultant precipitate. Theresultant solution was filtered under heating. Ammonia water was addedto the filtrate until the resultant solution became basic, followed bycooling with ice to precipitate a crystal. The crystal was recovered byfiltration, followed by washing and drying to obtain a crude product.The crude product was recrystallized from a mixture solvent ofn-hexane/benzene (1/1) to obtain 33.0 g of 2-amino-6-hexylbenzothiazole(Yield: 49.9 %).

Step ii) Production of zinc 5-hexyl-2-aminobenzenethiol

In a 1 liter-reaction vessel, 30.0 g (0.128M), 136 ml of water and 136.4g of KOH were placed, followed by heat-refluxing for 6.5 hours. Afterthe reaction, the reaction mixture was cooled to precipitate a crystalThen, ethanol was added to the resultant reaction mixture to dissolvethe crystal. To the solution, 5N-acetic acid aqueous solution was addeddropwise until the resultant mixture showed pH=9 to provide precipitate.The precipitate was filtered off and a solution of 8.9 g of ZnCl₂ in 40ml of 15 %-acetic acid aqueous solution was added dropwise to theresultant filtrate to precipitate a crystal. The crystal was recoveredby filtration after heating for 30 minutes at 70° C., followed bywashing with hot water, ethanol and water in succession. The resultantcrystal was dried to obtain 27.Q g Of zinc 5-hexyl-2-aminobenzenethiol(Yield: 73.4 %).

Step iii) Production of 2-(p-octylphenyl)-6-hexylbenzothiazole

20 ml of thionyl chloride was added to 3.74 g (16.0 mM) ofp-octylbenzoic acid, followed by heat-refluxing for 1 hour. After theheat-refluxing, excessive thionyl chloride was distilled off underreduced pressure, followed by distilling-off thereof with benzene. Tothe resultant acid chloride, 3.84 g (8.0 mM) of zinc5-hexyl-2-aminobenzenethiol was added, followed by stirring for 30minutes at 200° C. After the reaction, the reaction mixture was cooledunder room temperature. To the resultant reaction mixture, 40 ml ofdilute sodium hydroxide aqueous solution was added, followed byextraction with ethyl acetate, washing with water, drying with anhydrousmagnesium sulfate and distilling-off of the solvent to obtain a crudeproduct. The crude product was purified by silica gel columnchromatography (developing solvent: hexane/benzene=10/1) and treatedwith activated carbon followed by recrystallization from ethanol toobtain 3.45 g of 2-(p-octylphenyl)-6-hexylbenzothiazole (Yield: 52.9 %).##STR26##

Herein, the respective symbols denote the following phases; Iso.:isotropic phase; SmA: smectic A phase; and Cryst.: crystal.

SYNTHESIS EXAMPLE 2

2-(6-decyloxy-2-naphthyl)-5-butylbenzoxazole (Example Compound No.1-130) was synthesized through the following reaction scheme. ##STR27##

In a 50 ml-three-necked flask, 0.40 g (2.42 mM) of2-amino-4-butylphenol, 0.95 g (2.74 mM) of 6-decyloxy-2-naphthoylchloride and 10 ml of dioxane were placed. To the mixture. 0.81 ml ofpyridine was gradually added dropwise at about 75° C. under stirring,followed by heat-stirring for 20 minutes at about 80°-90° C. After thereaction, the reaction mixture was poured into 80 ml of water toprecipitate a crystal. The crystal was recovered by filtration, washedwith water and recrystallized from acetone to obtain 1.00 g of2-(6-decyloxy-2-naphthoylamino)-4-butylphenyl (yield: 86.8 %).

In a 20 ml-round-bottomed flask, 0.95 g (2.00 mM) of2-(6-decyloxy-2-naphthoylamino)-4-butylphenol, 0.07 g ofp-toluenesulfonic acid monohydrate and 8 ml of o-dichlorobenzene wereplaced, followed by stirring for 30 min. at 200°-203° C. After thereaction, o-dichlorobenzene was distilled-off under reduced pressure.The residue was purified by silica gel column chromatography (eluent:toluene/hexane=1/1) and recrystallized from acetone) to obtain 0.56 g of2-(6-decyloxy-2-naphthyl)-5-butyl-benzoxazole (yield: 61.3%). ##STR28##

Then, the compounds represented by the general formula (II) may besynthesized through the following reaction schemes A and B. ##STR29##

In a case where X³, X⁴ and Z¹ are respectively --O--, ##STR30## or it isalso possible to form a group of R³ --X³ --A⁵ -- or ##STR31## throughthe following steps (a) to (c):

(a) Hydroxyl group or carboxyl group combined with A⁵, A⁶ and A⁷ ismodified with addition of a protective group into a non-reactive or lessreactive group such as --OCH₃, ##STR32## capable of eliminationreaction.

(b) Ring closure is effected to form a thiazole ring.

(c) The protective group is eliminated and then the R⁷ --X³ --A⁵ -- or##STR33## structure is formed.

Specific examples of the mesomorphic compounds represented by theabove-mentioned general formula (II) may include those shown by thefollowing structural formulas. ##STR34##

Representative examples of synthesis of the compounds of the formula(II) are shown hereinbelow.

SYNTHESIS EXAMPLE 3

2-(4-hexylphenyl)-5-(4-pentanoyloxyphenyl)thiazole (Example Compound No.2-53) was synthesized through the following steps i)-iv).

Step i) 4-methoxyphenacyl bromide was prepared by brominating4-methoxyacetophenone with tetrabutylammonium tribromine in the samemanner as in "Bull. Chem. Soc. Jpn.", 60. 1159 (1987). ##STR35##

4-methoxyphenacylamine hydrochloride was synthesized from4-methoxyphenacyl bromide through the above reaction scheme according toa process shown in "Ber.", 44. 1542 (1911).

Step ii) ##STR36##

To a solution of 26.9 g (120 mM) of 4-hexylbenzoyl chloride in 206 ml ofpyridine, 22.2 g (110 mM) of 4-methoxyphenacylamine hydrochloride wasgradually added in 30 minutes under cooling and stirring at -10° to -5°C., followed by stirring for 30 minutes at -10° to -5° C. andheat-refluxing of 1 hour under stirring. After the reaction, thereaction mixture was cooled to room temperature and poured into 600 mlof cool water to precipitate a crystal. The crystal was recovered byfiltration, washed with water and recrystallized from ethanol to obtain19.6 g of 4-hexylbenzoyl-4'-methoxyphenacylamine (Yield: 50.5 %).

Step iii) ##STR37##

In a 300 ml-round-bottomed flask, 19.6 g (55.5 mM) of4-hexylbenzoyl-4'-methoxyphenacylamine, 24.3 g (60.1 mM) of Lawesson'sreagent and 97 ml of tetrahydrofuran were placed, followed byheat-refluxing for 1 hour under stirring. After the reaction, thereaction mixture was poured into a solution of 19 g of sodium hydroxidein 2 liters of water to precipitate a crystal. The crystal was recoveredby filtration, successively washed with water and ethanol andrecrystallized from ethanol to obtain 15.9 g of2-(4-hexylphenyl)-5-(4-methoxyphenyl)thiazole (Yield: 82.9

Then, in a 300 ml-three-necked flask, 13.9 g (39.3 mM) of2-(4-hexylphenyl)-5-(4-methoxyphenyl)tiazole, 76.5 ml of acetic acid and69.5 ml of 47%-hydrobromic acid were placed, followed by heat-stirringfor 16 hours at 100°-110° C. After the reaction, the reaction mixturewas poured into cool water, followed by extraction with ethyl acetate.The organic layer was successively washed with water, 5%-sodiumhydrogenecarbonate aqueous solution and water, followed bydistilling-off of the solvent under reduced pressure. The residue wasdissolved in a mixture solvent of ethanol/chloroform=1/1, followed bydecolorization with activated carbon and distilling-off of the solventunder reduced pressure. The resultant residue was recrystallized twotimes from toluene to obtain 10.0 g of2-(4-hexylphenyl)-5-(4-hydroxyphenyl)thiazole (Yield: 75.8 %).

Step iv) ##STR38##

To a solution of 0.60 g (1.78 mM) of2-(4-hexylphenyl)-5-(4-hydroxyphenyl)thiazole in 10 ml of pyridine, 0.36ml (3.03 mM) of pentanoyl chloride was added on an ice water bath understirring, followed by further stirring for 2 hours at room temperature.After the reaction, the reaction mixture was poured into 100 ml of icewater to precipitate a crystal. The crystal was recovered by filtrationand dissolved in toluene, followed by drying with anhydrous sodiumsulfate and distilling-off of the solvent. The residue was purified bysilica gel column chromatography (eluent: toluene) and recrystallizedfrom a mixture solvent of toluene-methanol to obtain 0.64 g of2-(4-hexylphenyl)-5-(4-pentanoyloxyphenyl)thiazole (Yield: 85.4%).##STR39##

SYNTHESIS EXAMPLE 4

2-(4-hexylphenyl)-5-(3-fluoro-4-heptanoyloxyphenyl)thiazole (ExampleCompound No. 2-148) was synthesized through the following reactionschemes in the same manner as in Synthesis Example 3. ##STR40##

Then, the compounds represented by the formula (III) may be synthesizedthrough processes as disclosed by, e.g., Japanese Laid-Open PatentApplication (JP-A) No. 22042/1988 and 122651/1988.

Specific examples of the mesomorphic compounds represented by theabove-mentioned general formula (III) may include those shown by thefollowing structural formulas. ##STR41##

Representative examples of synthesis of the compounds are shownhereinbelow.

SYNTHESIS EXAMPLE 5 Synthesis of Example Compound No. 3-24

1.00 g (4.16 mM) of p-2-fluorooctyloxyphenol was dissolved in a mixtureof 10 ml of pyridine and 5 ml of toluene, and a solution of 1.30 g (6.00mM) of trans-4-n-pentylcyclohexanecarbonyl chloride in 5 ml of toluenewas added dropwise thereto in 20 - 40 min. at below 5° C. After theaddition, the mixture was stirred overnight at room temperature toobtain a white precipitate.

After the reaction, the reaction product was extracted with benzene, andthe resultant benzene layer was washed with distilled water, followed bydrying with magnesium sulfate and distilling-off of the benzene,purification by silica gel column chromatography and recrystallizationfrom ethanol/methanol to obtain 1.20 g (2.85 mM) oftrans-4-n-pentylcyclohexanecarboxylic acid-p-2-fluorooctyloxypheny1-ester. (Yield: 68.6%)

NMR data (ppm):

0.83-2.83 ppm (34H, m),

4.00-4.50 ppm (2H, q),

7.11 ppm (4H, s)

IR data (cm⁻¹);

3456, 2928, 2852, 1742, 1508, 1470, 1248,

1200 1166, 1132, 854.

Phase transition temperature (°C.) ##STR42##

SYNTHESIS EXAMPLE 6 Synthesis of Example Compound No. 3-56

In a vessel sufficiently replaced with nitrogen, 0.40 g (3.0 mmol) of(-)-2-fluoroheptanol and 1.00 g (13 mmol) of dry pyridine were placedand stirred for 30 min. under cooling on an ice bath. Into the solution,0.69 g (3.6 mmol) of p-toluenesulfonyl chloride was added, and themixture was stirred for 5 hours. After the reaction, 10 ml of 1N-HCl wasadded, and the resultant mixture was subjected to two times ofextraction with 10 ml of methylene chloride. The extract liquid waswashed once with 10 ml of distilled water and dried with an appropriateamount of anhydrous sodium sulfate, followed by distilling-off of thesolvent to obtain 0.59 g (2.0 mmol) of (+)-2-fluoroheptylp-toluenesulfonate.

The yield was 66%, and the product showed the following optical rotationand IR data.

Optical rotation:

[α]_(D) ²⁶.4 +2.59 degrees (c=1, CHCl₃),

[α]₄₃₅ ²³.6 +9.58 degrees (c=1, CHCl₃)

IR (cm⁻¹):

2900, 2850, 1600, 1450, 1350, 1170, 1090,

980, 810, 660, 550

0.43 g (1.5 mmol) of the thus obtained (+)-2-fluoroheptylp-toluenesulfonate and 0.28 g (1.0 mmol) of5-octyl-2-(4-hydroxyphenyl)pyrimidine were mixed with 0.2 mlo±1-butanol, followed by sufficient stirring. To the solution wasquickly added a previously obtained alkaline solution of 0.048 g (1.2mmol) of sodium hydroxide in 1.0 ml of 1-butanol, followed by 5.5 hoursof heat-refluxing. After the reaction, 10 ml of distilled water wasadded, and the mixture was extracted respectively once with 10 ml ofbenzene and 5 ml of benzene, followed by drying with an appropriateamount of anhydrous sodium sulfate, distilling-off of the solvent andpurification by silica gel column chromatography (eluent: chloroform) toobtain 0.17 g (0.43 mmol) of objective(+)-5-octyl-2-[4-(2-fluoroheptyloxy)phenyl]pyrimidine.

The yield was 43 %, and the product showed the following opticalrotation and IR data.

Optical rotation:

[α]_(D) ²⁵.6 +0.44 degree (c=1, CHCl₃),

[α]₄₃₅ ²².4 +4.19 degrees (c=1, CHCl₃)

IR (cm⁻¹).

2900, 2850, 1600, 1580, 1420, 1250,

1160, 800, 720, 650, 550.

The liquid crystal composition according to the present invention may beobtained by mixing at least one species of the compound represented bythe formula (I), at least one species of the compound represented by theformula (II), optionally at least one species of the compoundrepresented by the formula (III), and another mesomorphic compound inappropriate proportions. The liquid crystal composition according to thepresent invention may preferably be formulated as a liquid crystalcomposition capable of utilizing ferroelectricity, particularly a liquidcrystal composition showing a chiral smectic phase.

Specific examples of another mesomorphic compound as described above mayinclude those denoted by the following formulas (IV) to (VIII).##STR43## wherein R₁ ' and R₂ ' respectively denote a linear or branchedalkyl group having 1-18 carbon atoms capable of including one or two ormore non-neighboring methylene groups which an be replaced with--CHCN--, --C(CH₃)CN--, --CHCl-- or --CHBr-- and capable of furtherincluding one or two or more non-neighboring methylene groups other thanthose directly connected to Z₁ ' or Z₂ ' which can be replaced with--O--, ##STR44## at least one of R₁ ' and R₂ ' being optically active;Z₁ ' and Z₂ ' respectively denote a single bond, --O--, ##STR45## a1 andb1 are respectively 0, 1 or 2 with the proviso that a1+b1=1 or 2.##STR46## wherein R₃ ' and R₄ ' respectively denote a linear or branchedalkyl group having 1-18 carbon atoms capable of including one or two ormore non-neighboring methylene groups which an be replaced with--CHCN--, --C(CH₃)CN--, --CHCl-- or --CHBr-- and capable of furtherincluding one or two or more non-neighboring methylene groups other thanthose directly connected to Z₃ ' or Z₄ ' which can be replaced with--O--, ##STR47## Z₃ ' and Z₄ ' respectively denote a single bond, --O--,##STR48## X₁ ' and X₂ ' respectively denote a single bond, ##STR49##--CH₂ O-- or --OCH₂ -- with the proviso that X₁ ' and X₂ ' cannotsimultaneously denote a single bond; A₁ ' denotes ##STR50## whereinwherein Y₁ ' denotes hydrogen, --CH₃ or --CF₃. ##STR51## wherein R₅ 'and R₆ ' respectively denote a linear or branched alkyl group having1-18 carbon atoms capable of including one or two or morenon-neighboring methylene groups which an be replaced with --CHCN--,--C(CH₃)CN--, --CHCl-- or --CHBr-- and capable of further including oneor two or more non-neighboring methylene groups other than thosedirectly connected to Z₅ ' or Z₆ ' which can be replaced with --O--,##STR52## A₂ ' denotes ##STR53## or a single bond; A₃ ' denotes##STR54## or a single bond with the proviso that A₂ ' and A₃ ' cannotsimultaneously denote a single bond; Z₅ ' and Z₆ ' respectively denote asingle bond, --O--, ##STR55## X₃ ' and X₄ ' respectively denote a singlebond, ##STR56## --CH₂ O-- or --CH₂ -- with the proviso that X₃ ' is asingle bond when A₂ ' is a single bond and X₄ ' is a single bond when A₃' is a single bond; and Y₂ ', Y₃ ' and Y₄ ' respectively denotehydrogen, halogen, --CH₃ or --CF₃. ##STR57## wherein R₇ ' and R₈ 'respectively denote a linear or branched alkyl group having 1-18 carbonatoms capable of including one or two or more non-neighboring methylenegroups which an be replaced with --CHCN--, --C(CH₃)CN--, --CHCl-- or--CHBr-- and capable of further including one or two or morenon-neighboring methylene groups other than those directly connected toZ₇ ' or Z₈ ' which can be replaced with --O--, ##STR58## A₄ ' denotes##STR59## Z₇ ' and Z₈ ' respectively a single bond, --O--, ##STR60## X₅' and X₆ ' respectively denote a single bond, ##STR61## --CH₂ O-- or--OCH₂ --; and a3 and b3 are respectively 0 or 1 with the proviso thata3 and b3 cannot simultaneously be 0. ##STR62## wherein R₉ ' denotes alinear or branched alkyl group having 1-18 carbon atoms; R₁₀ ' denotes alinear or branched alkyl group having 1-16 carbon atoms; A₅ ' denotes##STR63## A₆ ' denotes ##STR64## X₇ ' denotes a single bond, ##STR65##--CH₂ O-- or --OCH₂ --; X₈ ' denotes a single bond or ##STR66## Z₉ 'denotes a single bond, --O--, ##STR67## Z₁₀ ' denotes ##STR68## or--O--CH₂ CH₂ --; C* denotes an optically active asymmetric carbon atom.

In the formula (IV)-(VIII), preferred compounds thereof may includethose represented by the following formulas (IVa) to (VIIIe): ##STR69##

In formulating the liquid crystal composition according to the presentinvention, it is desirably that the mesomorphic compounds of theformulas (I) and (II) in total constitute 1-90 wt. %, preferably 2-80wt. %, further preferably 4-80%. of the resultant composition. Thecompound of the formula I) and the compound of the formula (II) maydesirably be contained in a weight ratio of 100:1-1:100, preferably70:1-1:70, further preferably 30:1-1:30.

The above proportional relationships may be desired also when two ormore species of either one or both of the compounds of the formulas (I)and (II) are used.

When the compounds of (I), (II) and (III) are used in combination forconstituting the liquid crystal composition according to the presentinvention, these compounds in total may desirably constitute 1-99 wt. %,4-90 wt. %, further preferably 6-80 wt. %, of the resultant liquidcrystal composition. The compounds of the formulas (I) and (II) in totaland the compound of the formula (III) may desirably be used in a weightratio of 1:30-100:1, preferably 1:20-50:1, more preferably 1:10-30:1.

Again the above proportional relationships regarding the compounds (I),(II) and (III) used in combination may be desired also when two or morespecies of one, two or all of the compounds of the formulas (I), (II)and (III) are used.

The ferroelectric liquid crystal device according to the presentinvention may preferably be prepared by heating the liquid crystalcomposition prepared as described above into an isotropic liquid undervacuum, filling a blank cell comprising a pair of oppositely spacedelectrode plates with the composition, gradually cooling the cell toform a liquid crystal layer and restoring the normal pressure.

FIG. 1 is a schematic sectional view of an embodiment of theferroelectric liquid crystal device prepared as described above forexplanation of the structure thereof.

Referring to FIG. 1, the ferroelectric liquid crystal device includes achiral smectic liquid crystal layer 1 disposed between a pair of glasssubstrates 2 each having thereon a transparent electrode 3 and aninsulating alignment control layer 4. Lead wires 6 are connected to theelectrodes so as to apply a driving voltage to the liquid crystal layer1 from a power supply 7. Outside the substrates 2, a pair of polarizers8 are disposed so as to modulate incident light I₀ from a light source 9in cooperation with the liquid crystal 1 to provide modulated light I.

Each of two glass substrates 2 is coated with a transparent electrode 3comprising a film of In₂ O₃, SnO₂ or ITO (indium-tin-oxide) to form anelectrode plate. Further thereon, an insulating alignment control layer4 is formed by rubbing a film of a polymer such as polyimide with gauzeor acetate fiber-planted cloth so as to align the liquid crystalmolecules in the rubbing direction. Further, it is also possible tocompose the alignment control layer of two layers, e.g., by firstforming an insulating layer of an inorganic material, such as siliconnitride, silicon nitride containing hydrogen, silicon carbide, siliconcarbide containing hydrogen, silicon oxide, boron nitride, boron nitridecontaining hydrogen, cerium oxide, aluminum oxide, zirconium oxide,titanium oxide, or magnesium fluoride, and forming thereon an alignmentcontrol layer of an organic insulating material, such as polyvinylalcohol, polyimide, polyamide-imide, polyester-imide, polyparaxylylene,polyester, polycarbonate, polyvinyl acetal, polyvinyl chloride,polyvinyl acetate, polyamide. polystyrene, cellulose resin, melamineresin, urea resin, acrylic resin, or photoresist resin. Alternatively,it is also possible to use a single layer of inorganic insulatingalignment control layer or organic insulating alignment control layer.An inorganic insulating alignment control layer may be formed by vapordeposition, while an organic insulating alignment control layer may beformed by applying a solution of an organic insulating material or aprecursor thereof in a concentration of 0.1 to 20 wt. %, preferably0.2-10 wt. %, by spinner coating, dip coating, screen printing, spraycoating or roller coating, followed by curing or hardening underprescribed hardening condition (e.g., by heating). The insulatingalignment control layer may have a thickness of ordinarily 30 Å-1micron, preferably 40-3000 Å, further preferably 40-1000 Å. The twoglass substrates 2 with transparent electrodes 3 (which may beinclusively referred to herein as "electrode plates") and further withinsulating alignment control layers 4 thereof are held to have aprescribed (but arbitrary) gap with a spacer 5. For example, such a cellstructure with a prescribed gap may be formed by sandwiching spacers ofsilica beads or alumina beads having a prescribed diameter with twoglass plates, and then sealing the periphery thereof with, e.g., anepoxy adhesive. Alternatively, a polymer film or glass fiber may also beused as a spacer. Between the two glass plates, a ferroelectric liquidcrystal is sealed up to provide a ferroelectric liquid crystal layer 1in a thickness of generally 0.5 to 20 microns, preferably 1 to 5microns.

The ferroelectric liquid crystal provided by the composition of thepresent invention may desirably assume a SmC* phase (chiral smectic Cphase) in a wide temperature range including room temperature(particularly, broad in a lower temperature side) and also shows widedrive voltage margin and drive temperature margin when contained in adevice.

Particularly, in order to show a good alignment characteristic to form auniform monodomain, the ferroelectric liquid crystal may show a phasetransition series comprising isotropic phase - Ch phase (cholestericphase) - SmA phase (smectic A phase) - SmC* phase (chiral smectic Cphase) on temperature decrease.

The transparent electrodes 3 are connected to the external power supply7 through the lead wires 6. Further, outside the glass substrates 2,polarizers 8 are applied. The device shown in FIG. 1 is of atransmission type and is provided with a light source 9.

FIG. 2 is a schematic illustration of a ferroelectric liquid crystalcell (device) for explaining operation thereof. Reference numerals 21aand 21b denote substrates (glass plates) on which a transparentelectrode of, e.g., In₂ O₃, SnO₂, ITO (indium-tin-oxide), etc., isdisposed, respectively. A liquid crystal of an SmC*-phase (chiralsmectic C phase) or SmH*-phase (chiral smectic H phase) in which liquidcrystal molecular layers 22 are aligned perpendicular to surfaces of theglass plates is hermetically disposed therebetween. Full lines 23 showliquid crystal molecules. Each liquid crystal molecule 23 has a dipolemoment (P⊥) 24 in a direction perpendicular to the axis thereof. Theliquid crystal molecules 23 continuously form a helical structure in thedirection of extension of the substrates. When a voltage higher than acertain threshold level is applied between electrodes formed on thesubstrates 21a and 21b, a helical structure of the liquid crystalmolecules 23 is unwound or released to change the alignment direction ofrespective liquid crystal molecules 23 so that the dipole moments (P⊥)24 are all directed in the direction of the electric field. The liquidcrystal molecules 23 have an elongated shape and show refractiveanisotropy between the long axis and the short axis thereof.Accordingly, it is easily understood that when, for instance, polarizersarranged in a cross nicol relationship, i.e., with their polarizingdirections crossing each other, are disposed on the upper and the lowersurfaces of the glass plates, the liquid crystal cell thus arrangedfunctions as a liquid crystal optical modulation device of which opticalcharacteristics vary depending upon the polarity of an applied voltage.

Further, when the liquid crystal cell is made sufficiently thin (e.g.,less than about 10 microns), the helical structure of the liquid crystalmolecules is unwound to provide a non-helical structure even in theabsence of an electric field, whereby the dipole moment assumes eitherof the two states, i.e., Pa in an upper direction 34a or Pb in a lowerdirection 34b as shown in FIG. 3, thus providing a bistable condition.When an electric field Ea or Eb higher than a certain threshold leveland different from each other in polarity as shown in FIG. 3 is appliedto a cell having the above-mentioned characteristics by using voltageapplication means 31a and 31b, the dipole moment is directed either inthe upper direction 34a or in the lower direction 34b depending on thevector of the electric field Ea or Eb. In correspondence with this, theliquid crystal molecules are oriented in either of a first stable state33a and a second stable state 33b.

When the above-mentioned ferroelectric liquid crystal is used as anoptical modulation element, it is possible to obtain two advantages.First is that the response speed is quite fast. Second is that theorientation of the liquid crystal shows bistability. The secondadvantage will be further explained, e.g., with reference to FIG. 3.When the electric field Ea is applied to the liquid crystal molecules,they are oriented in the first stable state 33a. This state is stablyretained even if the electric field is removed. On the other hand, whenthe electric field Eb of which direction is opposite to that of theelectric field Ea is applied thereto, the liquid crystal molecules areoriented to the second stable state 33b, whereby the directions ofmolecules are changed. This state is similarly stably retained even ifthe electric field is removed. Further, as long as the magnitude of theelectric field Ea or Eb being applied is not above a certain thresholdvalue, the liquid crystal molecules are placed in the respectiveorientation states.

Based on an arrangement described below and data format comprising imagedata accompanied with scanning line address data and by adoptingcommunication synchronization using a SYNC signal as shown in FIGS. 9and 10, there is provided a liquid crystal display apparatus of thepresent invention which uses the liquid crystal device according to thepresent invention as a display panel portion.

Referring to FIG. 9, the ferroelectric liquid crystal display apparatus101 includes a graphic controller 102, a display panel 103, a scanningline drive circuit 104, a data line drive circuit 105, a decoder 106, ascanning signal generator 107, a shift resistor 108, a line memory 109,a data signal generator 110, a drive control circuit 111, a graphiccentral processing unit (GCPU) 112, a host central processing unit (hostCPU) 113, and an image data storage memory (VRAM) 114.

Image data are generated in the graphic controller 102 in an apparatusbody and transferred to a display panel 103 by signal transfer meansshown in FIGS. 9 and 10. The graphic controller 102 principallycomprises a CPU (central processing unit, herein referred to as "GCPU")112 and a VRAM (video-RAM, image data storage memory) 114 and is incharge of management and communication of image data between a host CPU113 and the liquid crystal display apparatus (FLCD) 101. The control ofthe display apparatus is principally realized in the graphic controller102. A light source is disposed at the back of the display panel 103.

Hereinbelow, the present invention will be explained more specificallywith reference to examples. It is however to be understood that thepresent invention is not restricted to these examples.

EXAMPLE 1

A liquid crystal composition A was prepared by mixing the followingcompounds in respectively indicated proportions.

    __________________________________________________________________________    Structural formula                      wt. parts                             __________________________________________________________________________     ##STR70##                              9                                      ##STR71##                              8                                      ##STR72##                              10                                     ##STR73##                              8                                      ##STR74##                              3                                      ##STR75##                              3                                      ##STR76##                              3                                      ##STR77##                              3                                      ##STR78##                              15                                     ##STR79##                              15                                     ##STR80##                              8                                      ##STR81##                              9                                      ##STR82##                              6                                     __________________________________________________________________________

A liquid crystal composition 1-A was prepared by mixing the followingExample Compounds with the above prepared composition in therespectively indicated proportions.

    __________________________________________________________________________    Ex. Comp. No.                                                                         Structural formula             wt. parts                              __________________________________________________________________________    1-46                                                                                   ##STR83##                     5                                      1-79                                                                                   ##STR84##                     5                                      2-26                                                                                   ##STR85##                     7                                      2-55                                                                                   ##STR86##                     5                                      2-78                                                                                   ##STR87##                     5                                              Composition A                  73                                     __________________________________________________________________________

The above-prepared liquid crystal composition 1-A was used to prepare aliquid crystal device in combination with a blank cell prepared in thefollowing manner.

Two 0.7 mm-thick glass plates were provided and respectively coated withan ITO film to form an electrode for voltage application, which wasfurther coated with an insulating layer of vapor-deposited SiO₂. On theinsulating layer, a 0.2%-solution of silane coupling agent (KBM-602,available from Shinetsu Kagaku K. K.) in isopropyl alcohol was appliedby spinner coating at a speed of 2000 rpm for 15 second and subjected tohot curing treatment at 120° C. for 20 min.

Further, each glass plate provided with an ITO film and treated in theabove described manner was coated with a 1.0 %-solution of polyimideresin precursor (SP-510, available from Toray K. K.) indimethylacetoamide by a spinner coater rotating at 3000 rpm for 15seconds. Thereafter, the coating film was subjected to heat curing at300° C. for 60 min. to obtain about 120 Å-thick film. The coating filmwas rubbed with acetate fiber-planted cloth. The thus treated two glassplates were washed with isopropyl alcohol. After silica beads with anaverage particle size of 1.5 microns were dispersed on one of the glassplates, the two glass plates were applied to each other with a bondingsealing agent (Lixon Bond, available from Chisso K. K.) so that theirrubbed directions were parallel to each other and heated at 100° C. for60 min. to form a blank cell. The cell gap was found to be about 1.5microns as measured by a

Berek compensator.

Then, the above-prepared liquid crystal composition 1-A was heated intoan isotropic liquid, and injected into the above prepared cell undervacuum and, after sealing, was gradually cooled at a rate of 20° C./hourto 25° C. to prepare a ferroelectric liquid crystal device.

The ferroelectric liquid crystal device was subjected to measurement ofa driving voltage margin ΔV (=V₃ -V₁) by using the driving waveforms(bias ratio=1/3) described with reference to FIGS. 4 and 5 and settingΔt so as to provide V₁ of about 15 volts. The results are shown below.

    ______________________________________                                                   10° C.                                                                          25° C.                                                                            40° C.                                  ______________________________________                                        Voltage margin ΔV                                                                    14.2 V     14.1 V     13.7 V                                     (set Δt)                                                                             (630 μsec)                                                                            (185 μsec)                                                                            (76 μsec)                               ______________________________________                                    

Further, when the temperature was changed while the voltage (V_(S)+V_(I)) was set at a central value within the voltage margin at 25° C.(i.e., a central value of a voltage range capable of driving), thetemperature difference capable of driving (hereinafter called "(driving)temperature margin") was ±4.0° C.

Further, a contrast of 9.0 was attained at 25° C. during the driving.

COMPARATIVE EXAMPLE 1

A liquid crystal composition 1-AI was prepared by omitting Examplecompounds Nos. 2-26, 2-55 and 2-78 from the liquid crystal composition1-A, i.e., by adding only Example compound No. 1-46 and 1-79 to theliquid crystal composition and a liquid crystal composition 1-AII wasprepared by omitting Example compounds Nos. 1-46 and 1-79 from thecomposition 1-A, i.e., by adding only Example compounds Nos. 2-26, 2-55and 2-78 to the composition.

Ferroelectric liquid crystal devices A, 1-AI and 1-AII were prepared byusing the compositions A, 1-AI and 1-AII, respectively, instead of thecomposition 1-A, and subjected to measurement of driving voltage marginΔV, otherwise in the same manner as in Example 1. The results are shownbelow.

    ______________________________________                                        Voltage margin ΔV (set Δt)                                                10° C.                                                                           25° C.                                                                             40° C.                                   ______________________________________                                        A          9.0 V       8.5 V       8.0 V                                                (838 μsec)                                                                             (236 μsec)                                                                             (83 μsec)                                1-AI      10.1 V      10.5 V      10.0 V                                                (770 μsec)                                                                             (217 μsec)                                                                             (80 μsec)                                1-AII     10.5 V      10.0 V       9.5 V                                                (727 μsec)                                                                             (190 μsec)                                                                             (72 μsec)                                ______________________________________                                    

Further, the driving temperature margin with respect to 25° C. was ±1.8°C. for A, ±3.3° C. for 1-AI and ±3.0° C. for 1-AII.

As apparent from the above Example 1 and Comparative Example 1, theferroelectric liquid crystal device containing the liquid crystalcomposition 1-A according to the present invention provide wider drivingvoltage and temperature margins and showed a better performance ofretaining good images in resistance to changes in environmentaltemperature and cell gap.

EXAMPLE 2

Fifteen-types of ferroelectric liquid crystal devices were prepared inthe same manner as in Example 1 by equally using the composition 1-Aprepared in Example 1 except that 15 types of alignment films wereprepared by rubbing three types of polyimide films having differentthicknesses (i.e., 60 Å, 120 Å and 180 Å) with acetate fiber-plantedcloth at 5 degrees of different rubbing strengths (alignment-regulatingforces) by changing the moving speed of the acetate fiber-planted clothunder a constant pressing width of the cloth.

The ferroelectric liquid crystal devices prepared above were subjectedto microscopic observation of alignment states in the devices. Theresults of the observation are shown below.

    ______________________________________                                        Thickness of     Rubbing strength*1                                           coating film                                                                             1         2     3        4   5                                     ______________________________________                                         60 Å  ∘                                                                           ∘                                                                       ∘                                                                          ⊚                                                                  ⊚                      120 Å  ∘                                                                           ∘                                                                       ⊚*2                                                                     ⊚                                                                  ⊚                      180 Å  ∘                                                                           ⊚                                                                    ⊚                                                                       ⊚                                                                  ⊚                      ______________________________________                                         *1: A larger degree of rubbing strength is given by a smaller moving spee     of the rubbing cloth (i.e., a longer rubbing time). The respective degree     of rubbing strength corresponded to the following moving speeds of the        rubbing cloth:                                                                1: 70 mm/sec,                                                                 2: 60 mm/sec,                                                                 3: 50 mm/sec,                                                                 4: 40 mm/sec,                                                                 5: 30 mm/sec/                                                                 *2 The device used in Example 1.                                              The standards of evaluation of the alignment states were as follows:          ⊚: No alignment defects were observed, and a monodomain        with a good and uniform alignment characteristic was observed.                ∘: Alignment defects in the form of streaks were slightly         observed in a part of an area around silica beads.                       

COMPARATIVE EXAMPLE 2

Ferroelectric liquid crystal devices A, 1-AI and 1-AII were prepared byusing the compositions A, 1-AI and 1-AII prepared in Comparative Example1, respectively, instead of the composition 1-A prepared in Example 2,otherwise in the same manner as in Example 2. The devices were subjectedto observation of alignment states in the device. The results are shownbelow.

    ______________________________________                                        Thickness of     Rubbing strength                                             coating film                                                                             1         2     3        4   5                                     ______________________________________                                        <Device A>                                                                     60 Å                               x                                     120 Å                  x*1      x   x                                     180 Å            x     x        x   Δ                               <Device 1-AI>                                                                  60 Å  x         x     x        Δ                                                                           Δ                               120 Å  x         Δ                                                                             Δ*1                                                                              ∘                                                                     ∘                         180 Å  Δ   ∘                                                                       ∘                                                                          ∘                                                                     ∘                         <Device 1-AII>                                                                 60 Å            x     x        Δ                                                                           Δ                               120 Å  x         Δ                                                                             Δ*1                                                                              Δ                                                                           Δ                               180 Å  x         Δ                                                                             Δ  Δ                                                                           ∘                         ______________________________________                                         *1: The device used in Comparative Example 1.                                 ∘: Alignment defects in the form of streaks were slightly         observed in a part of an area around silica beads.                            Δ: Alignment states looked like a uniform monodomain, but alignment     defects in the form of streaks were observed over an entire area around       silica beads and zigzag defects were observed in a part of a display area     x: Zigzag defects were considerably observed.                                  : Zigzag defects were observed over a substantially entire display area      and ununiform alignment states result.                                   

As apparent from the above Example 2 and Comparative Example 2, theferroelectric liquid crystal device containing the liquid crystalcomposition 1-A according to the present invention provided a monodomainwith a good and uniform alignment characteristic when used in thedevice.

Further, as is understood from the above-mentioned Example 1 andComparative Example 1 and from the above Example 2 and ComparativeExample 2, some obstacles to commercialization of a practicalferroelectric liquid crystal device have been removed by using theliquid crystal composition 1-A according to the present invention.

EXAMPLE 3

A liquid crystal composition 3-A was prepared by mixing the followingexample compounds in the indicated proportions with the liquid crystalcomposition A prepared in Example 1.

    __________________________________________________________________________    Ex. Comp.                                                                     No.   Structural formula         wt. parts                                    __________________________________________________________________________    3-26                                                                                 ##STR88##                 6                                            3-80                                                                                 ##STR89##                 6                                            1-46                             5                                            1-79                             5                                            2-26                             7                                            2-55                             5                                            2-78                             5                                                  Composition A              73                                           __________________________________________________________________________

A ferroelectric liquid crystal device was prepared in the same manner asin Example 1 except that the above liquid crystal composition 3-A wasused, and the device was subjected to measurement of driving voltagemargin ΔV. The results of the measurement are shown below.

    ______________________________________                                                   10° C.                                                                          25° C.                                                                            40° C.                                  ______________________________________                                        Voltage margin ΔV                                                                    13.7 V     14.2 V     14.0 V                                     (set Δt)                                                                             (545 μsec)                                                                            (171 μsec)                                                                            (73 μsec)                               ______________________________________                                    

Further, the driving temperature margin with respect to 25° C. was ±3.9°C. A contrast of 11.0 was attained during the drive at the temperature.

COMPARATIVE EXAMPLE 3

A liquid crystal composition 3-AI was prepared by omitting Examplecompounds Nos. 2-26, 2-55 and 2-78 from the liquid crystal composition3-A, i.e., by adding only Example compounds Nos. 1-46, 1-79 3-26 and3-80 to the liquid Crystal composition A, and a liquid crystalcomposition 3-AII was prepared by omitting Example compounds Nos. 1-46and 1-79 from the composition 3-A. i.e.. by adding only Examplecompounds Nos. 2-26, 2-55, 2-78. 3-26 and 3-80 to the composition A.

Ferroelectric liquid crystal devices A, 3-AI and 3-AII were prepared byusing the compositions A, 3-AI and 3-AII, respectively, instead of thecomposition 3-A, and subjected to measurement of driving voltage marginΔV. otherwise in the same manner as in Example 3. The results are shownbelow.

    ______________________________________                                        Voltage margin ΔV (set Δt)                                                10° C.                                                                           25° C.                                                                             40° C.                                   ______________________________________                                        A          9.0 V       8.5 V       8.0 V                                                (838 μsec)                                                                             (236 μsec)                                                                             (83 μsec)                                3-AI      10.0 V      10.5 V      10.2 V                                                (610 μsec)                                                                             (200 μsec)                                                                             (75 μsec)                                3-AII     10.2 V      10.2 V       9.8 V                                                (600 μsec)                                                                             (165 μsec)                                                                             (64 μsec)                                ______________________________________                                    

Further, the driving temperature margin with respect to 25° C. was ±1.6°C. for A, ±3.1° C. for 3-AI and ±2 9° C. for 3-AII.

As apparent from the above Example 3 and Comparative Example 3, theferroelectric liquid crystal device containing the liquid crystalcomposition 3-B according to the present invention provided widerdriving voltage and temperature margins and showed a better performanceof retaining good images in resistance to changes in environmentaltemperature and cell gap.

EXAMPLE 4

Ferroelectric liquid crystal devices were prepared in the same manner asin Example 2 except for using the composition 3-A prepared in Example 3.

The ferroelectric liquid crystal devices prepared above were subjectedto microscopic observation of alignment states in the devices. Theresults of the observation are shown below.

    ______________________________________                                        Thickness of     Rubbing strength                                             coating film                                                                             1         2     3        4   5                                     ______________________________________                                         60 Å  ∘                                                                           ∘                                                                       ∘                                                                          ⊚                                                                  ⊚                      120 Å  ∘                                                                           ∘                                                                       ⊚*1                                                                     ⊚                                                                  ⊚                      180 Å  ∘                                                                           ⊚                                                                    ⊚                                                                       ⊚                                                                  ⊚                      ______________________________________                                         *1: The device used in Example 3.                                             ⊚: No alignment defects were observed, and a monodomain        with a good and uniform alignment characteristic was observed.                ∘: Alignment defects in the form of streaks were slightly         observed in a part of an area around silica beads.                       

COMPARATIVE EXAMPLE 4

Ferroelectric liquid crystal devices A, 3-AI and 1-AII were prepared byusing the compositions A, 3-AI and 3-AII prepared in Comparative Example3, respectively, instead of the composition 3-A prepared in Example 4,otherwise in the same manner as in Example 2. The devices were subjectedto observation of alignment states in the device. The results are shownbelow.

    ______________________________________                                        Thickness of     Rubbing strength                                             coating film                                                                             1         2     3        4   5                                     ______________________________________                                        <Device A>                                                                     60 Å                               x                                     120 Å                  x*1      x   x                                     180 Å  x         x     x        x   Δ                               <Device 3-AI>                                                                  60 Å  x         x     x        Δ                                                                           Δ                               120 Å  x         x     Δ*1                                                                              Δ                                                                           ∘                         180 Å  Δ   Δ                                                                             ∘                                                                          ∘                                                                     ∘                         <Device 3-AII>                                                                 60 Å            x     x        x   x                                     120 Å  x         x     x*1      x   Δ                               180 Å  x         x     Δ  Δ                                                                           Δ                               ______________________________________                                         *1: The device used in Comparative Example 3.                                 In the above, ∘, Δ, x and   are the same as defined in      the abovementioned Comparative Example 2.                                

As apparent from the above Example 4 and Comparative Example 4, theferroelectric liquid crystal device containing the liquid crystalcomposition 3-A according to the present invention provided a monodomainwith a good and uniform alignment characteristic when used in thedevice.

Further, apparent from the above-mentioned Example 3 and ComparativeExample 3 and from the above Example 4 and Comparative Example 4,obstacles to commercialization of a practical ferroelectric liquidcrystal device have been eliminated by using the liquid crystalcomposition 3-A according to the present invention.

EXAMPLE 5

A liquid crystal composition B was prepared by mixing the followingcompounds in the respectively indicated proportions.

    __________________________________________________________________________    Structural formula                      wt. parts                             __________________________________________________________________________     ##STR90##                              3                                      ##STR91##                              4                                      ##STR92##                              4                                      ##STR93##                              10                                     ##STR94##                              3                                      ##STR95##                              8                                      ##STR96##                              8                                      ##STR97##                              12                                     ##STR98##                              10                                     ##STR99##                              8                                      ##STR100##                             2                                      ##STR101##                             6                                      ##STR102##                             6                                      ##STR103##                             9                                      ##STR104##                             5                                      ##STR105##                             3                                     __________________________________________________________________________

A liquid crystal composition 5-B was prepared by mixing the followingExample Compounds with the above prepared composition B in therespectively indicated proportions.

    __________________________________________________________________________    Ex. Comp. No.                                                                         Structural formula            wt. parts                               __________________________________________________________________________    1-17                                                                                   ##STR106##                   3                                       1-59                                                                                   ##STR107##                   5                                       1-96                                                                                   ##STR108##                   3                                        1-133                                                                                 ##STR109##                   3                                       2-28                                                                                   ##STR110##                   5                                       2-39                                                                                   ##STR111##                   5                                        2-134                                                                                 ##STR112##                   2                                        2-137                                                                                 ##STR113##                   5                                               Composition B                 69                                      __________________________________________________________________________

A ferroelectric liquid crystal device 5-B was prepared in the samemanner as in Example 1 except that the liquid crystal composition 5-Bwas used instead of the composition 1-B. The device was subjected tomeasurement of driving voltage margin. The results of the measurementare shown below.

    ______________________________________                                                   10° C.                                                                          25° C.                                                                            40° C.                                  ______________________________________                                        Voltage margin ΔV                                                                    14.0 V     14.0 V     13.5 V                                     (set Δt)                                                                             (471 μsec)                                                                            (160 μsec)                                                                            (57 μsec)                               ______________________________________                                    

Further, the driving temperature margin with respect to 25° C. was ±4.0°C. A contrast of 9.0 was attained during the drive at the temperature.

COMPARATIVE EXAMPLE 5

A liquid crystal composition 5-BI was prepared by omitting Examplecompounds Nos. 2-28, 2-39, 2-134 and 2-137 from the liquid crystalcomposition 5-B prepared in Example 5, i.e., by adding only Examplecompounds Nos. 1-17, 1-59, 1-96 and 1-133 to the liquid crystalcomposition B, and a liquid crystal composition 5-BII was prepared byomitting Example compounds Nos. 1-17, 1-59, 1-96 and 1-133 from thecomposition 5-B, i.e., by adding only Example compounds Nos. 2-28, 2-39,2-134 and 2-137 to the composition B.

Ferroelectric liquid crystal devices B, 5-BI and 5-BII were prepared byusing the compositions B, 5-BI and 5-BII, respectively, instead of thecomposition 5-B, and subjected to measurement of driving voltage marginΔV, otherwise in the same manner as in Example 5. The results are shownbelow.

    ______________________________________                                        Voltage margin ΔV (set Δt)                                                10° C.                                                                           25° C.                                                                             40° C.                                   ______________________________________                                        B          8.3 V       8.5 V       6.5 V                                                (590 μsec)                                                                             (172 μsec)                                                                             (61 μsec)                                5-BI       9.8 V      10.0 V       9.5 V                                                (495 μsec)                                                                             (161 μsec)                                                                             (53 μsec)                                5-BII     10.5 V      11.0 V      10.5 V                                                (540 μsec)                                                                             (165 μsec)                                                                             (63 μsec)                                ______________________________________                                    

Further, the driving temperature margin with respect to 25° C. was ±1.9°C. for B, ±2.3° C. for 5-BI and ±2.8° C. for 5-BII.

As apparent from the above Example 5 and Comparative Example 5, theferroelectric liquid crystal device containing the liquid crystalcomposition 5-B according to the present invention provided widerdriving voltage and temperature margins and showed a better performanceof retaining good images in resistance to changes in environmentaltemperature and cell gap.

EXAMPLE 6

Ferroelectric liquid crystal devices were prepared in the same manner asin Example 5 except for using the composition 5-B prepared in Example 5.

The ferroelectric liquid crystal devices prepared above were subjectedto microscopic observation of alignment states in the devices. Theresults of the observation are shown below.

    ______________________________________                                        Thickness of     Rubbing strength                                             coating film                                                                             1         2     3        4   5                                     ______________________________________                                         60 Å  ∘                                                                           ∘                                                                       ⊚                                                                       ⊚                                                                  ⊚                      120 Å  ∘                                                                           ⊚                                                                    ⊚*1                                                                     ⊚                                                                  ⊚                      180 Å  ⊚                                                                        ⊚                                                                    ⊚                                                                       ⊚                                                                  ⊚                      ______________________________________                                         ⊚: No alignment defects were observed, and a monodomain        with a good and uniform alignment characteristic was observed.                ∘: Alignment defects in the form of streaks were slightly         observed in a part of an area around silica beads.                       

COMPARATIVE EXAMPLE 6

Ferroelectric liquid crystal devices B, 5-BI and 5-BII were prepared byusing the compositions B, 5-BI and 5-BII prepared in Comparative Example5, respectively, instead of the composition 5-B prepared in Example 6,otherwise in the same manner as in Example 6. The devices were subjectedto observation of alignment states in the device. The results are shownbelow.

    ______________________________________                                        Thickness of     Rubbing strength                                             coating film                                                                             1         2     3        4   5                                     ______________________________________                                        <Device B>                                                                     60 Å                           x   x                                     120 Å                  x*1      x   x                                     180 Å            x     x        x   x                                     <Device 5-BI>                                                                  60 Å  x         x     Δ  Δ                                                                           Δ                               120 Å  x         x     Δ*1                                                                              Δ                                                                           ∘                         180 Å  Δ   ∘                                                                       ∘                                                                          ∘                                                                     ∘                         <Device 5-BII>                                                                 60 Å  x         Δ                                                                             Δ  ∘                                                                     ∘                         120 Å  Δ   Δ                                                                             Δ*1                                                                              ∘                                                                     ∘                         180 Å  Δ   ∘                                                                       ∘                                                                          ∘                                                                     ∘                         ______________________________________                                         *1: The device used in Comparative Example 5.                                 ∘: Alignment defects in the form of streaks were slightly         observed in a part of an area around silica beads.                            Δ: Alignment states looked like a uniform monodomain, but alignment     defects in the form of streaks were observed over an entire area around       silica beads and zigzag defects were observed in a part of a display area     x: Zigzag defects were considerably observed.                                  : Zigzag defects were observed over a substantially entire display area      and ununiform alignment states result.                                   

As apparent from the above Example 6 and Comparative Example 6, theferroelectric liquid crystal device containing the liquid crystalcomposition 5-B according to the present invention provided a monodomainwith a good and uniform alignment characteristic when used in thedevice.

Further, apparent from the above-mentioned Example 5 and ComparativeExample 5 and from the above Example 6 and Comparative Example 6, someobstacles to commercialization of a practical ferroelectric liquidcrystal device have been removed by using the liquid crystal composition5-B according to the present invention.

EXAMPLE 7

A liquid crystal composition 7-B was prepared by mixing the followingexample compounds in the indicated proportions with the liquid crystalcomposition 5-B prepared in Example 5.

    __________________________________________________________________________    Ex. Comp.                                                                     No.   Structural formula          wt. parts                                   __________________________________________________________________________    3-6                                                                                  ##STR114##                 2                                           3-54                                                                                 ##STR115##                 3                                           3-81                                                                                 ##STR116##                 5                                           1-17                              3                                           1-59                              5                                           1-96                              3                                            1-133                            3                                           2-28                              5                                           2-39                              5                                            2-134                            2                                            2-137                            5                                                 Composition B               59                                          __________________________________________________________________________

A ferroelectric liquid crystal device was prepared in the same manner asin Example 1 except that the above liquid crystal composition 7-B wasused, and the device was subjected to measurement of driving voltagemargin. The results of the measurement are shown below.

    ______________________________________                                                   10° C.                                                                          25° C.                                                                            40° C.                                  ______________________________________                                        Voltage margin ΔV                                                                    12.5 V     13.0 V     12.5 V                                     (set Δt)                                                                             (378 μsec)                                                                            (118 μsec)                                                                            (46 μsec)                               ______________________________________                                    

Further, the driving temperature margin with respect to 25° C. was ±4.0°C. A contrast of 9.0 was attained during the drive at the temperature.

COMPARATIVE EXAMPLE 7

A liquid crystal composition 7-BI was prepared by omitting Examplecompounds Nos. 2-28, 2-39, 2-134 and 2-137 from the liquid crystalcomposition 7-B prepared in Example 7, i.e., by adding only Examplecompounds Nos. 1-17, 1-59, 1-96, 1-133, 3-6, 3-54 and 3-81 to the liquidcrystal composition B, and a liquid crystal composition 7-BII wasprepared by omitting Example compounds Nos. 1-17, 1-59, 1-96 and 1-133from the composition 7-B, i.e., by adding only Example compounds Nos.2-28, 2-39, 2-134, 2-137, 3-6, 3-54 and 3-81 to the composition B.

Ferroelectric liquid crystal devices B, 7-BI and 7-BII were prepared byusing the compositions B, 7-BI and 7-BII, respectively, instead of thecomposition 7-B, and subjected to measurement of driving voltage marginΔV, otherwise in the same manner as in Example 7. The results are shownbelow.

    ______________________________________                                        Voltage margin ΔV (set Δt)                                                10° C.                                                                           25° C.                                                                             40° C.                                   ______________________________________                                        B          8.3 V       8.5 V       6.5 V                                                (590 μsec)                                                                             (172 μsec)                                                                             (61 μsec)                                7-BI      10.8 V      10.7 V      10.2 V                                                (450 μsec)                                                                             (152 μsec)                                                                             (50 μsec)                                7-BII     10.2 V      10.3 V       9.8 V                                                (481 μsec)                                                                             (150 μsec)                                                                             (57 μsec)                                ______________________________________                                    

Further, the driving temperature margin with respect to 25° C. was ±1.8°C. for B, ±2.5° C. for 7-BI and ±3.1° C. for 7-BII.

As apparent from the above Example 7 and Comparative Example 7, theferroelectric liquid crystal device containing the liquid crystalcomposition 7-B according to the present invention provided widerdriving voltage and temperature margins and showed a better performanceof retaining good images in resistance to changes in environmentaltemperature and cell gap.

EXAMPLE 8

Ferroelectric liquid crystal devices were prepared in the same manner asin Example 2 except for using the composition 7-B prepared in Example 7.

The ferroelectric liquid crystal devices prepared above were subjectedto observation of alignment states in the devices. The results of theobservation are shown below.

    ______________________________________                                        Thickness of     Rubbing strength                                             coating film                                                                             1         2     3        4   5                                     ______________________________________                                         60 Å  ∘                                                                           ∘                                                                       ∘                                                                          ∘                                                                     ⊚                      120 Å  ∘                                                                           ∘                                                                       ⊚*1                                                                     ⊚                                                                  ⊚                      180 Å  ⊚                                                                        ⊚                                                                    ⊚                                                                       ⊚                                                                  ⊚                      ______________________________________                                         *1: The device used in Example 7.                                             ⊚: No alignment defects were observed, and a monodomain        with a good and uniform alignment characteristic was observed.                ∘: Alignment defects in the form of streaks were slightly         observed in a part of an area around silica beads.                       

COMPARATIVE EXAMPLE 8

Ferroelectric liquid crystal devices B, 7-BI and 7-BII were prepared byusing the compositions B, 7-BI and 7-BII prepared in Comparative Example7, respectively, instead of the composition 7-B prepared in Example 8,otherwise in the same manner as in Example 8. The devices were subjectedto observation of alignment states in the device. The results are shownbelow.

    ______________________________________                                        Thickness of     Rubbing strength                                             coating film                                                                             1         2     3        4   5                                     ______________________________________                                        <Device B>                                                                     60 Å                           x   x                                     120 Å                  x*1      x   x                                     180 Å  x         x     x        x   x                                     <Device 7-BI>                                                                  60 Å  x         x     x        Δ                                                                           Δ                               120 Å  x         x     Δ*1                                                                              Δ                                                                           Δ                               180 Å  x         Δ                                                                             Δ  Δ                                                                           Δ                               <Device 7-BII>                                                                 60 Å  x         Δ                                                                             Δ  Δ                                                                           ∘                         120 Å  Δ   Δ                                                                             ∘*1                                                                        ∘                                                                     ∘                         180 Å  Δ   ∘                                                                       ∘                                                                          ∘                                                                     ∘                         ______________________________________                                         *1: The device used in Comparative Example 7.                                 ∘: Alignment defects in the form of streaks were slightly         observed in a part of an area around silica beads.                            Δ : Alignment states looked like a uniform monodomain, but alignmen     defects in the form of streaks were observed over an entire area around       silica beads and zigzag defects were observed in a part of a display area     x: Zigzag defects were considerably observed.                                  : Zigzag defects were observed over a substantially entire display area      and ununiform alignment states result.                                   

As apparent from the above Example 8 and Comparative Example 8, theferroelectric liquid crystal device containing the liquid crystalcomposition 7-B according to the present invention provided a monodomainwith a good and uniform alignment characteristic when used in thedevice.

Further, apparent from the above-mentioned Example 7 and ComparativeExample 7 and from the above Example 8 and Comparative Example 8, someobstacles to commercialization of a practical ferroelectric liquidcrystal device have been removed by using the liquid crystal composition7-B according to the present invention.

EXAMPLE 9

A blank cell was prepared in the same manner as in Example 1 by using a2 % aqueous solution of polyvinyl alcohol resin (PVA-117, available fromKuraray K.K.) instead of the 1.5 %-solution of polyimide resin precursorin dimethylacetoamide on each electrode plate. A ferroelectric liquidcrystal device was prepared by filling the blank cell with the liquidcrystal composition 1-A prepared in Example 1. The liquid crystal devicewas subjected to measurement of driving voltage and temperature marginsin the same manner as in Example 1. The results are shown below.

    ______________________________________                                        Voltage margin (set Δt)                                                 10° C.                                                                         25° C.                                                                           40° C.                                                                          Temp. margin (at 25° C.)                    ______________________________________                                        14.1 V  14.1 V    13.6 V   ±4.0° C.                                 (628 μsec)                                                                         (186 μsec)                                                                           (76 μsec)                                                ______________________________________                                    

EXAMPLE 10

A blank cell was prepared in the same manner as in Example 1 except foromitting the SiO₂ layer to form an alignment control layer composed ofthe polyimide resin layer alone on each electrode plate. A ferroelectricliquid crystal devices were prepared by filling such a blank cell withliquid crystal composition 1-A prepared in Example 1. The liquid crystaldevice was subjected to measurement of driving voltage and temperaturemargings in the same manner as in Example 1. The results are shownbelow.

    ______________________________________                                        Voltage margin (set Δt)                                                 10° C.                                                                         25° C.                                                                           40° C.                                                                          Temp. margin (at 25° C.)                    ______________________________________                                        14.5 V  14.3 V    13.7 V   ±4.2° C.                                 (621 μsec)                                                                         (182 μsec)                                                                           (73 μsec)                                                ______________________________________                                    

As is apparent from the above Examples 9 and 10, also in the case of adifferent device structure, the device containing the ferroelectricliquid crystal composition 1-A according to the present inventionprovided wider driving voltage and temperature margins and showed abetter performance of retaining good images in resistance to changes inenvironmental temperature and cell gap.

EXAMPLES 11-20

Liquid crystal compositions 11-A to 15-A and 16-B to 20-B were preparedby replacing the example compounds and the liquid crystal compositionsused in Example 1 and 5 with example compounds and liquid crystalcompositions shown in the following Table 1. Ferroelectric liquidcrystal devices were prepared by respectively using these compositionsinstead of the composition 1-A, and subjected to measurement of drivingvoltage and temperature margins and observation of switching states inthe same manner as in Example 1. In the devices, a monodomain with agood and uniform alignment characteristic was observed. The results ofthe measurement are shown in the following Table 1.

                                      TABLE 1                                     __________________________________________________________________________                                                      Temp.                                                             Voltage margin (V)                                                                        margin                      Ex. No.                                                                              Example compound No. or liquid crystal composition                                                           Set Δt (μsec)                                                                    at 25° C.            (Comp. No.)                                                                          (weight parts)                 10° C.                                                                     25° C.                                                                     40° C.                                                                     (°C.)                __________________________________________________________________________    11     1-35,                                                                            1-46,                                                                            2-3,                                                                              2-30,                                                                             2-157,         A 13.7                                                                              13.7                                                                              12.9                                                                              ±4.0° C.          (11-A) 6  7  5   2   8              72                                                                              642 207 83                              12     1-47,                                                                            1-55,                                                                            1-111,                                                                            2-14,                                                                             2-72,          A 13.3                                                                              13.3                                                                              12.2                                                                              ±3.9° C.          (12-A) 8  8  1   7   3              73                                                                              652 210 85                              13     1-13,                                                                            1-51,                                                                            1-76,                                                                             1-135,                                                                            2-25,                                                                             2-125,     A 14.0                                                                              14.0                                                                              13.3                                                                              ±4.0° C.          (13-A) 5  5  3   7   6   2          72                                                                              638 206 82                              14     1-26,                                                                            1-62,                                                                            2-9,                                                                              2-39,                                                                             2-83,          A 14.0                                                                              14.1                                                                              13.1                                                                              ±4.1° C.          (14-A) 6  7  5   6   6              70                                                                              625 200 80                              15     1-8,                                                                             1-58,                                                                            1-102,                                                                            2-20,                                                                             2-138,         A 13.9                                                                              14.0                                                                              13.3                                                                              ±4.1° C.          (15-A) 8  8  1   7   5              71                                                                              609 197 78                              16     1-6,                                                                             1-74,                                                                            1-85,                                                                             2-52,                                                                             2-63,                                                                             2-193,     B 14.1                                                                              14.1                                                                              13.3                                                                              ±4.2° C.          (16-B) 7  5  6   5   5   3          69                                                                              467 157 55                              17     1-37,                                                                            1-77,                                                                            1-101,                                                                            2-16,                                                                             2-171,                                                                            2-180,     B 14.1                                                                              14.2                                                                              13.2                                                                              ±4.2° C.          (17-B) 6  5  5   5   3   5          71                                                                              481 165 59                              18     1-22,                                                                            1-91,                                                                            1-97,                                                                             2-82,                                                                             2-158,                                                                            2-160,     B 13.9                                                                              14.0                                                                              12.9                                                                              ±4.0° C.          (18-B) 7  5  3   7   3   5          70                                                                              473 159 56                              19     1-36,                                                                            1-38,                                                                            1-122,                                                                            2-75,                                                                             2.86,                                                                             2-168,                                                                            3-24,                                                                             3-30,                                                                            B 13.9                                                                              14.1                                                                              12.9                                                                              ±4.0° C.          (19-B) 6  3  5   6   5   5   8   2    345 110 43                              20     1-57,                                                                            1-76,                                                                            1-128,                                                                            2-35,                                                                             2-110,                                                                            2-176,                                                                            3-63,                                                                             3-72                                                                             B 13.8                                                                              14.0                                                                              13.7                                                                              ±4.0° C.          (20-B) 5  3  3   6   6   5   7   3    337 112 45                              21     1-11,                                                                            1-62,                                                                            1-73,                                                                             1-106,                                                                            2-63,                                                                             2-80,                                                                             2-169,                                                                            3-63,                                                                            B 12.1                                                                              13.1                                                                              10.8                                                                              ±3.9° C.          (21-B) 3  7  6   2   6   8   4   11 53                                                                              355 116 46                              __________________________________________________________________________

As apparent from the above Examples 11-20, the ferroelectric liquidcrystal devices containing the liquid crystal compositions 11-A to 15-Aand 16-B to 20-B respectively, according to the present inventionprovided wider driving voltage and temperature margins and showed a goodalignment characteristic and better performance of retaining good imagesin resistance to changes in environmental temperature and cell gap.

Further, the liquid crystal device containing the liquid crystalcomposition according to the present invention provided a decreasedtemperature dependence of response speed (smaller ratio of set Δt (10°C./40° C.)).

Thus, early commercialization of a liquid crystal device utilizingferroelectricity of a liquid crystal can be expected by using the liquidcrystal composition according to the present invention.

As described hereinabove, according to the present invention, there isprovided a liquid crystal composition which is easily aligned by simplerubbing treatment and provides a monodomain with a good and uniformalignment characteristic and with no defects.

Further, the liquid crystal device using such a liquid crystalcomposition according to the present invention shows a good switchingcharacteristic and provides a wider driving voltage margin and a widertemperature margin affording satisfactory drive of entire pixels evenwhen some degree of temperature fluctuation is present over a displayarea comprising the pixels of a liquid crystal device.

Still further, according to the present invention, there is provided adisplay apparatus and display method utilizing the liquid crystal devicedescribed above as a display unit, which provide good displaycharacteristics in combination with a light source, a drive circuit,etc.

What is claimed is:
 1. A liquid crystal composition, comprising:at leastone mesomorphic compound represented by the following formula (I):

    R.sup.1 --X.sup.1 --A.sup.1 --B--A.sup.2 --X.sup.2 --R.sup.2(I),

wherein R¹ and R² independently denote a linear or branched alkyl grouphaving 1-18 carbon atoms capable of including one or non-neighboring twoor more methylene groups which can be replaced with at least one speciesof --O--, --CO--, --COO--, --OCO--, --OCOO-- or --CH(X)-- with theproviso that --O-- cannot directly be connected to --O-- and X denoteshalogen; X¹ and X² independently denotes a single bond, --O--, --COO--,--OCO-- or --CO--; B denotes ##STR117## A¹ denotes a single bond,##STR118## A² denotes a single bond, --A³ -- or --A³ --A⁴ -- wherein A³and A⁴ independently denote any one of A¹, ##STR119## and Y¹ and Y²independently denote any one of hydrogen, F, Cl, Br, --CH₃, --CN and--CF₃ ; and at least one mesomorphic compound represented by thefollowing formula (II): ##STR120## wherein R³ and R⁴ independentlydenote a linear or branched alkyl group having 1-18 carbon atoms capableof including one or non-neighboring two or more methylene groups whichcan be replaced with at least one species of --O--, --CO--, --COO--,--OCO--, --OCOO-- or --CH(X)-- with the proviso that --O-- cannotdirectly be connected to --O-- and X denotes halogen; X³ and X⁴independently denotes a single bond, --O--, --COO--, --OCO-- or --CO--;Z¹ denotes a single bond, --COO-- or --OCO--; A⁵, A⁶ and A⁷independently denote a single bond, ##STR121## Y³ and Y⁴ independentlydenote hydrogen, halogen, --CH₃ or --CF₃ ; and k is 0 or 1 with theproviso that X³ is a single bond when A⁵ is a single bond, and X⁴ is asingle bond when A⁶ is a single bond and k is
 0. 2. A liquid crystalcomposition according to claim 1, which further comprises a mesomorphiccompound represented by the following formula (III): ##STR122## whereinR⁵ denotes a linear or branched alkyl group having 1-18 carbon atomsoptionally substituted by an alkyl or alkoxy; X⁵ denotes a single bond,--P--, --COO-- or --OCO--; Z² denotes a single bond, --COO--, --OCO--,--COS-- or --SCO--; X⁶ denotes --OCH₂ --, --COOCH₂ --, --OCO-- or##STR123## wherein k is an integer of 1-4; ##STR124## denotes ##STR125##and u is an integer of 1-12.
 3. A liquid crystal composition accordingto claim 1, wherein the mesomorphic compound of the formula (I) isrepresented by any one of the following formulas (Ia)-(Ig): ##STR126##wherein R¹ and R² independently denote a linear or branched alkyl grouphaving 1-18 carbon atoms capable of including one or non-neighboring twoor more methylene groups which can be replaced with at least one speciesof --O--, --CO--, --COO--, --OCO--, --OCOO-- or --CH(X)-- with theproviso that --O-- cannot directly be connected to --O-- and X denoteshalogen; X¹ and X² independently denotes a single bond, --O--, --COO--,--OCO-- or --CO--; B denotes ##STR127## and Y¹ and Y² independentlydenote any one of hydrogen, F, Cl, Br, --CH₃, --CN and --CF₃.
 4. Aliquid crystal composition according to claim 3, wherein B in theformulas (Ia)-(Ig) denotesor ##STR128##
 5. A liquid crystal compositionaccording to claim 3, wherein X¹ and X² in the formulas (Ia)-(Ig)independently denote a single bond, --O--, --COO-- or --OCO--.
 6. Aliquid crystal composition according to claim 3, wherein Y¹ and Y² inthe formulas (Ia)-(Ig) independently denote Cl or F.
 7. A liquid crystalcomposition according to claim 1, wherein R¹ and R² in the formula (I)independently denote any one of the following groups (I-i) to(I-iv):(I-i) an n-alkyl group having 1-16 carbon atoms; (I-ii)##STR129## wherein m is an integer of 0-6 and n is an integer of 1-8;(I-iii) ##STR130## wherein r is an integer of 0-6, s is 0 or 1, and t isan integer of 1-12; and (I-iv) ##STR131## wherein p is 0 or 1 and x isan integer of 4-14.
 8. A liquid crystal composition according to claim1, wherein the mesomorphic compound of the formula (II) is representedby any one of the following formulas (IIa)-(IIq): ##STR132## wherein R³and R⁴ independently denote a linear or branched alkyl group having 1-18carbon atoms capable of including one or non-neighboring two or moremethylene groups which can be replaced with at least one species of--O--, --CO--, --COO--, --OCO--, --OCOO-- or --CH(X)-- with the provisothat --O-- cannot directly be directly to --O-- and X denotes halogen;X³ and X⁴ independently denotes a single bond, --O--, --COO--, --OCO--or --CO--; Z¹ denotes a single bond, --COO-- or --OCO; and Y³ and Y⁴independently denote hydrogen, halogen, --CH₃ or --CF₃.
 9. A liquidcrystal composition according to claim 1, wherein the mesomorphiccompound of the formula (II) is represented by any one of the followingformulas (IIaa) to (IIna): ##STR133## wherein R³ and R⁴ independentlydenote a linear or branched alkyl group having 1-18 carbon atoms capableof including one or non-neighboring two or more methylene groups whichcan be replaced with at least one species of --O--, --CO--, --COO--,--OCO--, --OCOO-- or --CH(X)-- with the proviso that --O-- cannotdirectly be connected to --O-- and X denotes halogen; X³ and X⁴independently denotes a single bond, --O--, --COO--, --OCO-- or --CO--;and Y³ and Y⁴ independently denote hydrogen, halogen, --CH₃ or --CF₃.10. A liquid crystal composition according to claim 1, wherein R³ and R⁴in the formula (II) respectively denote any one of the following groups(II-i) to (II-iv):(II-i) an n-alkyl group having 2-16 carbon atoms;(II-ii) ##STR134## wherein m' is an integer of 0-6 and n' is an integerof 2-8; (II-iii) ##STR135## wherein r' is an integer of 0-6, s' is 0 or1, and t' is an integer of 1-12; and (II-iv) ##STR136## wherein p' is 0or 1 and x' is an integer of 1-14.
 11. A liquid crystal compositionaccording to claim 2, wherein the mesomorphic compound of the formula(III) is represented by any one of the following formulas (IIIa)-(IIIf):##STR137## wherein R⁵ denotes a linear or branched alkyl group having1-18 carbon atoms optionally substituted by an alkoxy; X⁵ denotes asingle bond, --O--, --COO-- or --OCO--; X⁶ denotes --OCH₂ --, --COOCH₂--, --OCO-- or ##STR138## wherein k is an integer of 1-4; and u is aninteger of 1-12.
 12. A liquid crystal composition according to claim 11,wherein X⁵ and X⁶ in the formulas (IIIa) to (IIIf) denote any one of thefollowing combinations (III-i) to (III-v):(III-i) X⁵ is a single bondand X⁶ is --O--CH₂ --; (III-ii) X⁵ is a single bond and X⁶ is --COO--CH₂--; (III-iii) X⁵ is a single bond and X⁶ is --OCO--; (III-iv) X⁵ is--O-- and X⁶ is --O--CH₂ --; and (III-v) X⁵ is --O-- and X⁶ is --COOCH₂--.
 13. A liquid crystal composition according to claim 1, whichcomprises 1-90 wt. % in total of the mesomorphic compounds of theformulas (I) and (II).
 14. A liquid crystal composition according toclaim 1, which comprises 2-80 wt. % in total of the mesomorphiccompounds of the formulas (I) and (II).
 15. A liquid crystal compositionaccording to claim 1, which comprises 4-80 wt. % in total of themesomorphic compounds of the formulas (I) and (II).
 16. A liquid crystalcomposition according to claim 2, which comprises 1-99 wt. % in total ofthe mesomorphic compounds of the formulas (I), (II) and (III).
 17. Aliquid crystal composition according to claim 2, which comprises 4-90wt. % in total of the mesomorphic compounds of the formulas (I), (II)and (III).
 18. A liquid crystal composition according to claim 2, whichcomprises 6-80 wt. % in total of the mesomorphic compounds of theformulas (I), (II) and (III).
 19. A liquid crystal composition accordingto claim 1 or 2, which has a chiral smectic phase.
 20. A liquid crystaldevice, comprising a pair of electrode plates and a liquid crystalcomposition according to claim 1 or 2 disposed between the electrodeplates.
 21. A liquid crystal device according to claim 20, which furthercomprises an insulating alignment control layer.
 22. A liquid crystaldevice according to claim 21, wherein the insulating alignment controllayer has been subjected to rubbing.
 23. A liquid crystal deviceaccording to claim 20, wherein the liquid crystal composition isdisposed in a thickness suppressing formation of a helical structure ofliquid crystal molecules between the electrode plates.
 24. A displayapparatus comprising a liquid crystal device according to claim 20, andvoltage application means for driving the liquid crystal device.
 25. Adisplay apparatus comprising a liquid crystal device according to claim24, voltage application means for driving the liquid crystal device, anda drive circuit.
 26. A display apparatus comprising a liquid crystaldevice according to claim 24, voltage application means for driving theliquid crystal device, and a light source.
 27. A display methodcomprising:providing a liquid crystal composition according to any oneof claims 1-18; and switching the alignment direction of liquid crystalmolecules by applying voltage to the liquid crystal composition toeffect display.
 28. A display method comprising:providing a liquidcrystal composition according to claim 19; and switching the alignmentdirection of liquid crystal molecules by applying voltage to the liquidcrystal composition to effect display.
 29. A display method,comprising:providing a liquid crystal device according to claim 20; andswitching the alignment direction of liquid crystal molecules byapplying voltage to the liquid crystal composition disposed between theelectrode plates to effect display.
 30. A display method,comprising:providing a liquid crystal device according to claim 21; andswitching the alignment direction of liquid crystal molecules byapplying voltage to the liquid crystal composition disposed between theelectrode plates to effect display.
 31. A display method,comprising:providing a liquid crystal device according to claim 22; andswitching the alignment direction of liquid crystal molecules byapplying voltage to the liquid crystal composition disposed between theelectrode plates to effect display.
 32. A display method,comprising:providing a liquid crystal device according to claim 23; andswitching the alignment direction of liquid crystal molecules byapplying voltage to the liquid crystal composition disposed between theelectrode plates to effect display.